Fixed operation time frequency sweeps for an analyte sensor

ABSTRACT

Sensors that detect an analyte via spectroscopic techniques using non-optical frequencies such as in the radio or microwave frequency range of the electromagnetic spectrum or optical frequencies in the visible range of the electromagnetic spectrum. An analyte sensor described herein includes a detector array having at least one transmit element and at least one receive element. The transmit element and the receive element can be antennas or light emitting elements such as light emitting diodes. The sensor is controlled to implement first and second frequency sweeps and the frequency sweeps have at least one overlapping range of frequencies where the operation times are the same between the first and second frequency sweeps.

FIELD

This disclosure relates generally to apparatus, systems and methods ofdetecting an analyte via spectroscopic techniques using an analytesensor that includes at least one transmit element and at least onereceive element, where the transmit element and the receive elementoperate in the radio or microwave frequency range of the electromagneticspectrum or operate in the visible range of the electromagneticspectrum.

BACKGROUND

There is interest in being able to detect and/or measure an analytewithin a target. One example is measuring glucose in biological tissue.In the example of measuring glucose in a patient, current analytemeasurement methods are invasive in that they perform the measurement ona bodily fluid such as blood for fingerstick or laboratory-based tests,or on fluid that is drawn from the patient often using an invasivetranscutaneous device. There are non-invasive methods that claim to beable to perform glucose measurements in biological tissues. However,many of the non-invasive methods generally suffer from: lack ofspecificity to the analyte of interest, such as glucose; interferencefrom temperature fluctuations; interference from skin compounds (i.e.sweat) and pigments; and complexity of placement, i.e. the sensingdevice resides on multiple locations on the patient's body.

SUMMARY

This disclosure relates generally to apparatus, systems and methods ofdetecting an analyte via spectroscopic techniques using non-opticalfrequencies such as in the radio or microwave frequency range of theelectromagnetic spectrum or optical frequencies in the visible range ofthe electromagnetic spectrum. An analyte sensor described hereinincludes a detector array having at least one transmit element and atleast one receive element. The transmit element and the receive elementcan be antennas or light emitting elements such as light emittingdiodes. In the following description, the transmit element and thereceive element, whether they are antennas or light emitting diodes, mayeach be referred to as a detector element.

The transmit element is controlled so as to implement at least first andsecond frequency sweeps. Additional frequency sweeps can be implementedwith each frequency sweep being like the first and second frequencysweeps. The first frequency sweep occurs over a first frequency rangefrom a start frequency to an end frequency, and the second frequencysweep occurs over a second frequency range from a start frequency to anend frequency. In one embodiment, the first frequency range and thesecond frequency range at least partially overlap one another. Inanother embodiment, the first frequency range and the second frequencyrange are identical to one another. The first frequency range and thesecond frequency range where they overlap have first frequency steps andsecond frequency steps, respectively. In the overlapping range, thefirst frequency steps are the same as the second frequency steps. Eachfrequency step of the first frequency steps and the second frequencysteps has an associated operation time, and the operation times of thefirst frequency steps of the first frequency range are identical to theoperation times of the second frequency steps of the second frequencyrange. Because each the first and second frequency sweeps, at leastwhere they overlap one another, are conducted substantially identicallyto one another, a more accurate comparison between the results of eachfrequency sweep can be conducted.

In one embodiment described herein, a sensor system can include adetector array having at least one transmit element and at least onereceive element. The at least one transmit element is positioned andarranged to transmit a transmit signal into a target, and the at leastone receive element is positioned and arranged to detect a responseresulting from transmission of the transmit signal by the at least onetransmit element into the target. A transmit circuit is electricallyconnectable to the at least one transmit element, where the transmitcircuit is configured to generate the transmit signal to be transmittedby the at least one transmit element, and the transmit signal is in aradio frequency or visible range of the electromagnetic spectrum. Areceive circuit is electrically connectable to the at least one receiveelement, where the receive circuit is configured to receive the responsedetected by the at least one receive element. A control system isconnected to the transmit circuit and is configured to implement atleast first and second frequency sweeps by the at least one transmitelement. The first frequency sweep occurs over a first frequency rangefrom a start frequency to an end frequency, the second frequency sweepoccurs over a second frequency range from a start frequency to an endfrequency, and the first frequency range and the second frequency rangeoverlap one another. The first frequency range and the second frequencyrange where they overlap have first frequency steps and second frequencysteps, respectively. The first frequency steps are the same as thesecond frequency steps, each of the frequency steps of the firstfrequency steps and the second frequency steps has an associatedoperation time, and the operation times of the first frequency steps areidentical to the operation times of the second frequency steps.

In another embodiment described herein, a method of operating a sensorsystem is described. The sensor system includes a detector array havingat least one transmit element and at least one receive element, wherethe at least one transmit element is positioned and arranged to transmita transmit signal into a target, and the at least one receive element ispositioned and arranged to detect a response resulting from transmissionof the transmit signal by the at least one transmit element into thetarget. A transmit circuit is electrically connectable to the at leastone transmit element where the transmit circuit is configured togenerate the transmit signal to be transmitted by the at least onetransmit element, and the transmit signal is in a radio frequency orvisible range of the electromagnetic spectrum. In addition, a receivecircuit is electrically connectable to the at least one receive elementwhere the receive circuit is configured to receive a response detectedby the at least one receive element. The method includes controlling thesensor system to implement at least a first frequency sweep and a secondfrequency sweep by the at least one transmit element, where the firstfrequency sweep occurs over a first frequency range from a startfrequency to an end frequency, the second frequency sweep occurs over asecond frequency range from a start frequency to an end frequency, andthe first frequency range and the second frequency range overlap oneanother. The first frequency range and the second frequency range wherethey overlap have first frequency steps and second frequency steps,respectively. The first frequency steps are the same as the secondfrequency steps, each frequency step of the first frequency steps andthe second frequency steps has an associated operation time, and theoperation times of the first frequency steps are identical to theoperation times of the second frequency steps.

DRAWINGS

FIG. 1 is a schematic depiction of an analyte sensor system with ananalyte sensor relative to a target according to an embodiment.

FIGS. 2A-C illustrate different example orientations of antenna arraysthat can be used in an embodiment of a sensor system described herein.

FIGS. 3A-3C illustrate different examples of transmit and receiveantennas with different geometries.

FIGS. 4A, 4B, 4C and 4D illustrate additional examples of differentshapes that the ends of the transmit and receive antennas can have.

FIG. 5 illustrates another example of an antenna array that can be used.

FIG. 6 is a schematic depiction of a portion of another embodiment of ananalyte sensor system with an analyte sensor that uses electromagneticenergy in the form of light to perform analyte sensing described herein.

FIG. 7 illustrates another example of an analyte sensor system with ananalyte sensor that uses electromagnetic energy in the form of light toperform analyte sensing described herein.

FIG. 8 depicts an example operation of the sensor system of FIG. 6.

FIG. 9 is a flowchart of a method for detecting an analyte according toan embodiment.

FIG. 10 is a flowchart of analysis of a response according to anembodiment.

FIG. 11 depicts an example of a frequency sweep.

Like reference numbers represent like parts throughout.

DETAILED DESCRIPTION

The following is a detailed description of apparatus, systems andmethods of detecting an analyte via spectroscopic techniques usingnon-optical frequencies such as in the radio or microwave frequencybands of the electromagnetic spectrum or optical frequencies in thevisible range of the electromagnetic spectrum. An analyte sensordescribed herein includes a detector array having at least one transmitelement and at least one receive element. The transmit element and thereceive element can be antennas (FIGS. 1-5) or light emitting elementssuch as light emitting diodes (FIGS. 6-7). In the following description,the transmit element and the receive element, whether they are antennasor light emitting diodes, may each be referred to as a detector element.

The following description together with FIGS. 1-5 will initiallydescribe the analyte sensor system as including a detector array havingtwo or more antennas. Later in the following description, together withFIGS. 6-7, the analyte sensor system is described as including adetector array that includes two or more light emitting devices such aslight emitting diodes (LEDs). The detector array having two or more LEDsmay also be described as an LED array.

In one embodiment, the sensor systems described herein can be used todetect the presence of at least one analyte in a target. In anotherembodiment, the sensor systems described herein can detect an amount ora concentration of the at least one analyte in the target. The targetcan be any target containing at least one analyte of interest that onemay wish to detect. The target can be human or non-human, animal ornon-animal, biological or non-biological. For example, the target caninclude, but is not limited to, human tissue, animal tissue, planttissue, an inanimate object, soil, a fluid, genetic material, or amicrobe. Non-limiting examples of targets include, but are not limitedto, a fluid, for example blood, interstitial fluid, cerebral spinalfluid, lymph fluid or urine, human tissue, animal tissue, plant tissue,an inanimate object, soil, genetic material, or a microbe.

The detection by the sensors described herein can be non-invasivemeaning that the sensor remains outside the target, such as the humanbody, and the detection of the analyte occurs without requiring removalof fluid or other removal from the target, such as the human body. Inthe of sensing in the human body, this non-invasive sensing may also bereferred to as in vivo sensing. In other embodiments, the sensorsdescribed herein may be an in vitro sensor where the material containingthe analyte has been removed, for example from a human body.

The analyte(s) can be any analyte that one may wish to detect. Theanalyte can be human or non-human, animal or non-animal, biological ornon-biological. For example, the analyte(s) can include, but is notlimited to, one or more of blood glucose, blood alcohol, white bloodcells, or luteinizing hormone. The analyte(s) can include, but is notlimited to, a chemical, a combination of chemicals, a virus, a bacteria,or the like. The analyte can be a chemical included in another medium,with non-limiting examples of such media including a fluid containingthe at least one analyte, for example blood, interstitial fluid,cerebral spinal fluid, lymph fluid or urine, human tissue, animaltissue, plant tissue, an inanimate object, soil, genetic material, or amicrobe. The analyte(s) may also be a non-human, non-biological particlesuch as a mineral or a contaminant.

The analyte(s) can include, for example, naturally occurring substances,artificial substances, metabolites, and/or reaction products. Asnon-limiting examples, the at least one analyte can include, but is notlimited to, insulin, acarboxyprothrombin; acylcarnitine; adeninephosphoribosyl transferase; adenosine deaminase; albumin;alpha-fetoprotein; amino acid profiles (arginine (Krebs cycle),histidine/urocanic acid, homocysteine, phenylalanine/tyrosine,tryptophan); andrenostenedione; antipyrine; arabinitol enantiomers;arginase; benzoylecgonine (cocaine); biotinidase; biopterin; c-reactiveprotein; carnitine; pro-BNP; BNP; troponin; carnosinase; CD4;ceruloplasmin; chenodeoxycholic acid; chloroquine; cholesterol;cholinesterase; conjugated 1-β hydroxy-cholic acid; cortisol; creatinekinase; creatine kinase MM isoenzyme; cyclosporin A; d-penicillamine;de-ethylchloroquine; dehydroepiandrosterone sulfate; DNA (acetylatorpolymorphism, alcohol dehydrogenase, alpha 1-antitrypsin, cysticfibrosis, Duchenne/Becker muscular dystrophy, analyte-6-phosphatedehydrogenase, hemoglobin A, hemoglobin S, hemoglobin C, hemoglobin D,hemoglobin E, hemoglobin F, D-Punjab, beta-thalassemia, hepatitis Bvirus, HCMV, HIV-1, HTLV-1, Leber hereditary optic neuropathy, MCAD,RNA, PKU, Plasmodium vivax, sexual differentiation, 21-deoxycortisol);desbutylhalofantrine; dihydropteridine reductase; diptheria/tetanusantitoxin; erythrocyte arginase; erythrocyte protoporphyrin; esterase D;fatty acids/acylglycines; free β-human chorionic gonadotropin; freeerythrocyte porphyrin; free thyroxine (FT4); free tri-iodothyronine(FT3); fumarylacetoacetase; galactose/gal-1-phosphate;galactose-1-phosphate uridyltransferase; gentamicin; analyte-6-phosphatedehydrogenase; glutathione; glutathione perioxidase; glycocholic acid;glycosylated hemoglobin; halofantrine; hemoglobin variants;hexosaminidase A; human erythrocyte carbonic anhydrase I;17-alpha-hydroxyprogesterone; hypoxanthine phosphoribosyl transferase;immunoreactive trypsin; lactate; lead; lipoproteins ((a), B/A-1, β);lysozyme; mefloquine; netilmicin; phenobarbitone; phenytoin;phytanic/pristanic acid; progesterone; prolactin; prolidase; purinenucleoside phosphorylase; quinine; reverse tri-iodothyronine (rT3);selenium; serum pancreatic lipase; sissomicin; somatomedin C; specificantibodies (adenovirus, anti-nuclear antibody, anti-zeta antibody,arbovirus, Aujeszky's disease virus, dengue virus, Dracunculusmedinensis, Echinococcus granulosus, Entamoeba histolytica, enterovirus,Giardia duodenalisa, Helicobacter pylori, hepatitis B virus, herpesvirus, HIV-1, IgE (atopic disease), influenza virus, Leishmaniadonovani, leptospira, measles/mumps/rubella, Mycobacterium leprae,Mycoplasma pneumoniae, Myoglobin, Onchocerca volvulus, parainfluenzavirus, Plasmodium falciparum, polio virus, Pseudomonas aeruginosa,respiratory syncytial virus, rickettsia (scrub typhus), Schistosomamansoni, Toxoplasma gondii, Trepenoma pallidium, Trypanosomacruzi/rangeli, vesicular stomatis virus, Wuchereria bancrofti, yellowfever virus); specific antigens (hepatitis B virus, HIV-1);succinylacetone; sulfadoxine; theophylline; thyrotropin (TSH); thyroxine(T4); thyroxine-binding globulin; trace elements; transferrin;UDP-galactose-4-epimerase; urea; uroporphyrinogen I synthase; vitamin A;white blood cells; and zinc protoporphyrin.

The analyte(s) can also include one or more chemicals introduced intothe target. The analyte(s) can include a marker such as a contrastagent, a radioisotope, or other chemical agent. The analyte(s) caninclude a fluorocarbon-based synthetic blood. The analyte(s) can includea drug or pharmaceutical composition, with non-limiting examplesincluding ethanol; cannabis (marijuana, tetrahydrocannabinol, hashish);inhalants (nitrous oxide, amyl nitrite, butyl nitrite,chlorohydrocarbons, hydrocarbons); cocaine (crack cocaine); stimulants(amphetamines, methamphetamines, Ritalin, Cylert, Preludin, Didrex,PreState, Voranil, Sandrex, Plegine); depressants (barbiturates,methaqualone, tranquilizers such as Valium, Librium, Miltown, Serax,Equanil, Tranxene); hallucinogens (phencyclidine, lysergic acid,mescaline, peyote, psilocybin); narcotics (heroin, codeine, morphine,opium, meperidine, Percocet, Percodan, Tussionex, Fentanyl, Darvon,Talwin, Lomotil); designer drugs (analogs of fentanyl, meperidine,amphetamines, methamphetamines, and phencyclidine, for example,Ecstasy); anabolic steroids; and nicotine. The analyte(s) can includeother drugs or pharmaceutical compositions. The analyte(s) can includeneurochemicals or other chemicals generated within the body, such as,for example, ascorbic acid, uric acid, dopamine, noradrenaline,3-methoxytyramine (3MT), 3,4-Dihydroxyphenylacetic acid (DOPAC),Homovanillic acid (HVA), 5-Hydroxytryptamine (5HT), and5-Hydroxyindoleacetic acid (FHIAA).

The sensor systems illustrated in FIGS. 1-5 and in FIGS. 6-7 operate bytransmitting an electromagnetic signal (whether in the radio ormicrowave frequency range of the electromagnetic spectrum in FIGS. 1-5or in the visible range of the electromagnetic spectrum in FIGS. 6-7)toward and into a target using a transmit element such as a transmitantenna or a transmit LED. A returning signal that results from thetransmission of the transmitted signal is detected by a receive elementsuch as a receive antenna or a photodetector. The signal(s) detected bythe receive element can be analyzed to detect the analyte based on theintensity of the received signal(s) and reductions in intensity at oneor more frequencies where the analyte absorbs the transmitted signal.

FIGS. 1-5 illustrate a non-invasive analyte sensor system that uses twoor more antennas including a transmit antenna and a receive antenna. Thetransmit antenna and the receive antenna can be located near the targetand operated as further described herein to assist in detecting at leastone analyte in the target. The transmit antenna transmits a signal,which has at least two frequencies in the radio or microwave frequencyrange, toward and into the target. The signal with the at least twofrequencies can be formed by separate signal portions, each having adiscrete frequency, that are transmitted separately at separate times ateach frequency. In another embodiment, the signal with the at least twofrequencies may be part of a complex signal that includes a plurality offrequencies including the at least two frequencies. The complex signalcan be generated by blending or multiplexing multiple signals togetherfollowed by transmitting the complex signal whereby the plurality offrequencies are transmitted at the same time. One possible technique forgenerating the complex signal includes, but is not limited to, using aninverse Fourier transformation technique. The receive antenna detects aresponse resulting from transmission of the signal by the transmitantenna into the target containing the at least one analyte of interest.

The transmit antenna and the receive antenna are decoupled (which mayalso be referred to as detuned or the like) from one another. Decouplingrefers to intentionally fabricating the configuration and/or arrangementof the transmit antenna and the receive antenna to minimize directcommunication between the transmit antenna and the receive antenna,preferably absent shielding. Shielding between the transmit antenna andthe receive antenna can be utilized. However, the transmit antenna andthe receive antenna are decoupled even without the presence ofshielding.

An example of detecting an analyte using a non-invasive spectroscopysensor operating in the radio or microwave frequency range of theelectromagnetic spectrum is described in WO 2019/217461, the entirecontents of which are incorporated herein by reference. The signal(s)detected by the receive antenna can be complex signals including aplurality of signal components, each signal component being at adifferent frequency. In an embodiment, the detected complex signals canbe decomposed into the signal components at each of the differentfrequencies, for example through a Fourier transformation. In anembodiment, the complex signal detected by the receive antenna can beanalyzed as a whole (i.e. without demultiplexing the complex signal) todetect the analyte as long as the detected signal provides enoughinformation to make the analyte detection. In addition, the signal(s)detected by the receive antenna can be separate signal portions, eachhaving a discrete frequency.

Referring now to FIG. 1, an embodiment of a non-invasive analyte sensorsystem with a non-invasive analyte sensor 5 is illustrated. The sensor 5is depicted relative to a target 7 that contains an analyte of interest9. In this example, the sensor 5 is depicted as including an antennaarray that includes a transmit antenna/element 11 (hereinafter “transmitantenna 11”) and a receive antenna/element 13 (hereinafter “receiveantenna 13”). The sensor 5 further includes a transmit circuit 15, areceive circuit 17, and a controller 19. As discussed further below, thesensor 5 can also include a power supply, such as a battery (not shownin FIG. 1). In some embodiments, power can be provided from mains power,for example by plugging the sensor 5 into a wall socket via a cordconnected to the sensor 5.

The transmit antenna 11 is positioned, arranged and configured totransmit a signal 21 that is in the radio frequency (RF) or microwaverange of the electromagnetic spectrum into the target 7. The transmitantenna 11 can be an electrode or any other suitable transmitter ofelectromagnetic signals in the radio frequency (RF) or microwave range.The transmit antenna 11 can have any arrangement and orientationrelative to the target 7 that is sufficient to allow the analyte sensingto take place. In one non-limiting embodiment, the transmit antenna 11can be arranged to face in a direction that is substantially toward thetarget 7.

The signal 21 transmitted by the transmit antenna 11 is generated by thetransmit circuit 15 which is electrically connectable to the transmitantenna 11. The transmit circuit 15 can have any configuration that issuitable to generate a transmit signal to be transmitted by the transmitantenna 11. Transmit circuits for generating transmit signals in the RFor microwave frequency range are well known in the art. In oneembodiment, the transmit circuit 15 can include, for example, aconnection to a power source, a frequency generator, and optionallyfilters, amplifiers or any other suitable elements for a circuitgenerating an RF or microwave frequency electromagnetic signal. In anembodiment, the signal generated by the transmit circuit 15 can have atleast two discrete frequencies (i.e. a plurality of discretefrequencies), each of which is in the range from about 10 kHz to about100 GHz. In another embodiment, each of the at least two discretefrequencies can be in a range from about 300 MHz to about 6000 MHz. Inan embodiment, the transmit circuit 15 can be configured to sweepthrough a range of frequencies that are within the range of about 10 kHzto about 100 GHz, or in another embodiment a range of about 300 MHz toabout 6000 MHz. In an embodiment, the transmit circuit 15 can beconfigured to produce a complex transmit signal, the complex signalincluding a plurality of signal components, each of the signalcomponents having a different frequency. The complex signal can begenerated by blending or multiplexing multiple signals together followedby transmitting the complex signal whereby the plurality of frequenciesare transmitted at the same time.

The receive antenna 13 is positioned, arranged, and configured to detectone or more electromagnetic response signals 23 that result from thetransmission of the transmit signal 21 by the transmit antenna 11 intothe target 7 and impinging on the analyte 9. The receive antenna 13 canbe an electrode or any other suitable receiver of electromagneticsignals in the radio frequency (RF) or microwave range. In anembodiment, the receive antenna 13 is configured to detectelectromagnetic signals having at least two frequencies, each of whichis in the range from about 10 kHz to about 100 GHz, or in anotherembodiment a range from about 300 MHz to about 6000 MHz. The receiveantenna 13 can have any arrangement and orientation relative to thetarget 7 that is sufficient to allow detection of the response signal(s)23 to allow the analyte sensing to take place. In one non-limitingembodiment, the receive antenna 13 can be arranged to face in adirection that is substantially toward the target 7.

The receive circuit 17 is electrically connectable to the receiveantenna 13 and conveys the received response from the receive antenna 13to the controller 19. The receive circuit 17 can have any configurationthat is suitable for interfacing with the receive antenna 13 to convertthe electromagnetic energy detected by the receive antenna 13 into oneor more signals reflective of the response signal(s) 23. Theconstruction of receive circuits are well known in the art. The receivecircuit 17 can be configured to condition the signal(s) prior toproviding the signal(s) to the controller 19, for example throughamplifying the signal(s), filtering the signal(s), or the like.Accordingly, the receive circuit 17 may include filters, amplifiers, orany other suitable components for conditioning the signal(s) provided tothe controller 19. In an embodiment, at least one of the receive circuit17 or the controller 19 can be configured to decompose or demultiplex acomplex signal, detected by the receive antenna 13, including aplurality of signal components each at different frequencies into eachof the constituent signal components. In an embodiment, decomposing thecomplex signal can include applying a Fourier transform to the detectedcomplex signal. However, decomposing or demultiplexing a receivedcomplex signal is optional. Instead, in an embodiment, the complexsignal detected by the receive antenna can be analyzed as a whole (i.e.without demultiplexing the complex signal) to detect the analyte as longas the detected signal provides enough information to make the analytedetection.

The controller 19 controls the operation of the sensor 5. The controller19, for example, can direct the transmit circuit 15 to generate atransmit signal to be transmitted by the transmit antenna 11. Thecontroller 19 further receives signals from the receive circuit 17. Thecontroller 19 can optionally process the signals from the receivecircuit 17 to detect the analyte(s) 9 in the target 7. In oneembodiment, the controller 19 may optionally be in communication with atleast one external device 25 such as a user device and/or a remoteserver 27, for example through one or more wireless connections such asBluetooth, wireless data connections such a 4G, 5G, LTE or the like, orWi-Fi. If provided, the external device 25 and/or remote server 27 mayprocess (or further process) the signals that the controller 19 receivesfrom the receive circuit 17, for example to detect the analyte(s) 9. Ifprovided, the external device 25 may be used to provide communicationbetween the sensor 5 and the remote server 27, for example using a wireddata connection or via a wireless data connection or Wi-Fi of theexternal device 25 to provide the connection to the remote server 27.

With continued reference to FIG. 1, the sensor 5 may include a sensorhousing 29 (shown in dashed lines) that defines an interior space 31.Components of the sensor 5 may be attached to and/or disposed within thehousing 29. For example, the transmit antenna 11 and the receive antenna13 are attached to the housing 29. In some embodiments, the antennas 11,13 may be entirely or partially within the interior space 31 of thehousing 29. In some embodiments, the antennas 11, 13 may be attached tothe housing 29 but at least partially or fully located outside theinterior space 31. In some embodiments, the transmit circuit 15, thereceive circuit 17 and the controller 19 are attached to the housing 29and disposed entirely within the sensor housing 29.

The receive antenna 13 is decoupled or detuned with respect to thetransmit antenna 11 such that electromagnetic coupling between thetransmit antenna 11 and the receive antenna 13 is reduced. Thedecoupling of the transmit antenna 11 and the receive antenna 13increases the portion of the signal(s) detected by the receive antenna13 that is the response signal(s) 23 from the target 7, and minimizesdirect receipt of the transmitted signal 21 by the receive antenna 13.The decoupling of the transmit antenna 11 and the receive antenna 13results in transmission from the transmit antenna 11 to the receiveantenna 13 having a reduced forward gain (S₂₁) and an increasedreflection at output (S₂₂) compared to antenna systems having coupledtransmit and receive antennas.

In an embodiment, coupling between the transmit antenna 11 and thereceive antenna 13 is 95% or less. In another embodiment, couplingbetween the transmit antenna 11 and the receive antenna 13 is 90% orless. In another embodiment, coupling between the transmit antenna 11and the receive antenna 13 is 85% or less. In another embodiment,coupling between the transmit antenna 11 and the receive antenna 13 is75% or less.

Any technique for reducing coupling between the transmit antenna 11 andthe receive antenna 13 can be used. For example, the decoupling betweenthe transmit antenna 11 and the receive antenna 13 can be achieved byone or more intentionally fabricated configurations and/or arrangementsbetween the transmit antenna 11 and the receive antenna 13 that issufficient to decouple the transmit antenna 11 and the receive antenna13 from one another.

For example, in one embodiment described further below, the decouplingof the transmit antenna 11 and the receive antenna 13 can be achieved byintentionally configuring the transmit antenna 11 and the receiveantenna 13 to have different geometries from one another. Intentionallydifferent geometries refers to different geometric configurations of thetransmit and receive antennas 11, 13 that are intentional. Intentionaldifferences in geometry are distinct from differences in geometry oftransmit and receive antennas that may occur by accident orunintentionally, for example due to manufacturing errors or tolerances.

Another technique to achieve decoupling of the transmit antenna 11 andthe receive antenna 13 is to provide appropriate spacing between eachantenna 11, 13 that is sufficient to decouple the antennas 11, 13 andforce a proportion of the electromagnetic lines of force of thetransmitted signal 21 into the target 7 thereby minimizing oreliminating as much as possible direct receipt of electromagnetic energyby the receive antenna 13 directly from the transmit antenna 11 withouttraveling into the target 7. The appropriate spacing between eachantenna 11, 13 can be determined based upon factors that include, butare not limited to, the output power of the signal from the transmitantenna 11, the size of the antennas 11, 13, the frequency orfrequencies of the transmitted signal, and the presence of any shieldingbetween the antennas. This technique helps to ensure that the responsedetected by the receive antenna 13 is measuring the analyte 9 and is notjust the transmitted signal 21 flowing directly from the transmitantenna 11 to the receive antenna 13. In some embodiments, theappropriate spacing between the antennas 11, 13 can be used togetherwith the intentional difference in geometries of the antennas 11, 13 toachieve decoupling.

In one embodiment, the transmit signal that is transmitted by thetransmit antenna 11 can have at least two different frequencies, forexample upwards of 7 to 12 different and discrete frequencies. Inanother embodiment, the transmit signal can be a series of discrete,separate signals with each separate signal having a single frequency ormultiple different frequencies.

In one embodiment, the transmit signal (or each of the transmit signals)can be transmitted over a transmit time that is less than, equal to, orgreater than about 300 ms. In another embodiment, the transmit time canbe less than, equal to, or greater than about 200 ms. In still anotherembodiment, the transmit time can be less than, equal to, or greaterthan about 30 ms. The transmit time could also have a magnitude that ismeasured in seconds, for example 1 second, 5 seconds, 10 seconds, ormore. In an embodiment, the same transmit signal can be transmittedmultiple times, and then the transmit time can be averaged. In anotherembodiment, the transmit signal (or each of the transmit signals) can betransmitted with a duty cycle that is less than or equal to about 50%.

FIGS. 2A-2C illustrate examples of antenna arrays 33 that can be used inthe sensor system 5 and how the antenna arrays 33 can be oriented. Manyorientations of the antenna arrays 33 are possible, and any orientationcan be used as long as the sensor 5 can perform its primary function ofsensing the analyte 9.

In FIG. 2A, the antenna array 33 includes the transmit antenna 11 andthe receive antenna 13 disposed on a substrate 35 which may besubstantially planar. This example depicts the array 33 disposedsubstantially in an X-Y plane. In this example, dimensions of theantennas 11, 13 in the X and Y-axis directions can be considered lateraldimensions, while a dimension of the antennas 11, 13 in the Z-axisdirection can be considered a thickness dimension. In this example, eachof the antennas 11, 13 has at least one lateral dimension (measured inthe X-axis direction and/or in the Y-axis direction) that is greaterthan the thickness dimension thereof (in the Z-axis direction). In otherwords, the transmit antenna 11 and the receive antenna 13 are eachrelatively flat or of relatively small thickness in the Z-axis directioncompared to at least one other lateral dimension measured in the X-axisdirection and/or in the Y-axis direction.

In use of the embodiment in FIG. 2A, the sensor and the array 33 may bepositioned relative to the target 7 such that the target 7 is below thearray 33 in the Z-axis direction or above the array 33 in the Z-axisdirection whereby one of the faces of the antennas 11, 13 face towardthe target 7. Alternatively, the target 7 can be positioned to the leftor right sides of the array 33 in the X-axis direction whereby one ofthe ends of each one of the antennas 11, 13 face toward the target 7.Alternatively, the target 7 can be positioned to the sides of the array33 in the Y-axis direction whereby one of the sides of each one of theantennas 11, 13 face toward the target 7.

The sensor 5 can also be provided with one or more additional antennaarrays in addition the antenna array 33. For example, FIG. 2A alsodepicts an optional second antenna array 33 a that includes the transmitantenna 11 and the receive antenna 13 disposed on a substrate 35 a whichmay be substantially planar. Like the array 33, the array 33 a may alsobe disposed substantially in the X-Y plane, with the arrays 33, 33 aspaced from one another in the X-axis direction.

In FIG. 2B, the antenna array 33 is depicted as being disposedsubstantially in the Y-Z plane. In this example, dimensions of theantennas 11, 13 in the Y and Z-axis directions can be considered lateraldimensions, while a dimension of the antennas 11, 13 in the X-axisdirection can be considered a thickness dimension. In this example, eachof the antennas 11, 13 has at least one lateral dimension (measured inthe Y-axis direction and/or in the Z-axis direction) that is greaterthan the thickness dimension thereof (in the X-axis direction). In otherwords, the transmit antenna 11 and the receive antenna 13 are eachrelatively flat or of relatively small thickness in the X-axis directioncompared to at least one other lateral dimension measured in the Y-axisdirection and/or in the Z-axis direction.

In use of the embodiment in FIG. 2B, the sensor and the array 33 may bepositioned relative to the target 7 such that the target 7 is below thearray 33 in the Z-axis direction or above the array 33 in the Z-axisdirection whereby one of the ends of each one of the antennas 11, 13face toward the target 7. Alternatively, the target 7 can be positionedin front of or behind the array 33 in the X-axis direction whereby oneof the faces of each one of the antennas 11, 13 face toward the target7. Alternatively, the target 7 can be positioned to one of the sides ofthe array 33 in the Y-axis direction whereby one of the sides of eachone of the antennas 11, 13 face toward the target 7.

In FIG. 2C, the antenna array 33 is depicted as being disposedsubstantially in the X-Z plane. In this example, dimensions of theantennas 11, 13 in the X and Z-axis directions can be considered lateraldimensions, while a dimension of the antennas 11, 13 in the Y-axisdirection can be considered a thickness dimension. In this example, eachof the antennas 11, 13 has at least one lateral dimension (measured inthe X-axis direction and/or in the Z-axis direction) that is greaterthan the thickness dimension thereof (in the Y-axis direction). In otherwords, the transmit antenna 11 and the receive antenna 13 are eachrelatively flat or of relatively small thickness in the Y-axis directioncompared to at least one other lateral dimension measured in the X-axisdirection and/or in the Z-axis direction.

In use of the embodiment in FIG. 2C, the sensor and the array 33 may bepositioned relative to the target 7 such that the target 7 is below thearray 33 in the Z-axis direction or above the array 33 in the Z-axisdirection whereby one of the ends of each one of the antennas 11, 13face toward the target 7. Alternatively, the target 7 can be positionedto the left or right sides of the array 33 in the X-axis directionwhereby one of the sides of each one of the antennas 11, 13 face towardthe target 7. Alternatively, the target 7 can be positioned in front ofor in back of the array 33 in the Y-axis direction whereby one of thefaces of each one of the antennas 11, 13 face toward the target 7.

The arrays 33, 33 a in FIGS. 2A-2C need not be oriented entirely withina plane such as the X-Y plane, the Y-Z plane or the X-Z plane. Instead,the arrays 33, 33 a can be disposed at angles to the X-Y plane, the Y-Zplane and the X-Z plane.

Decoupling Antennas Using Differences in Antenna Geometries

As mentioned above, one technique for decoupling the transmit antenna 11from the receive antenna 13 is to intentionally configure the transmitantenna 11 and the receive antenna 13 to have intentionally differentgeometries. Intentionally different geometries refers to differences ingeometric configurations of the transmit and receive antennas 11, 13that are intentional, and is distinct from differences in geometry ofthe transmit and receive antennas 11, 13 that may occur by accident orunintentionally, for example due to manufacturing errors or toleranceswhen fabricating the antennas 11, 13.

The different geometries of the antennas 11, 13 may manifest itself, andmay be described, in a number of different ways. For example, in a planview of each of the antennas 11, 13 (such as in FIGS. 3A-C), the shapesof the perimeter edges of the antennas 11, 13 may be different from oneanother. The different geometries may result in the antennas 11, 13having different surface areas in plan view. The different geometriesmay result in the antennas 11, 13 having different aspect ratios in planview (i.e. a ratio of their sizes in different dimensions; for example,as discussed in further detail below, the ratio of the length divided bythe width of the antenna 11 may be different than the ratio of thelength divided by the width for the antenna 13). In some embodiments,the different geometries may result in the antennas 11, 13 having anycombination of different perimeter edge shapes in plan view, differentsurface areas in plan view, and/or different aspect ratios. In someembodiments, the antennas 11, 13 may have one or more holes formedtherein (see FIG. 2B) within the perimeter edge boundary, or one or morenotches formed in the perimeter edge (see FIG. 2B).

So as used herein, a difference in geometry or a difference ingeometrical shape of the antennas 11, 13 refers to any intentionaldifference in the figure, length, width, size, shape, area closed by aboundary (i.e. the perimeter edge), etc. when the respective antenna 11,13 is viewed in a plan view.

The antennas 11, 13 can have any configuration and can be formed fromany suitable material that allows them to perform the functions of theantennas 11, 13 as described herein. In one embodiment, the antennas 11,13 can be formed by strips of material. A strip of material can includea configuration where the strip has at least one lateral dimensionthereof greater than a thickness dimension thereof when the antenna isviewed in a plan view (in other words, the strip is relatively flat orof relatively small thickness compared to at least one other lateraldimension, such as length or width when the antenna is viewed in a planview as in FIGS. 3A-C). A strip of material can include a wire. Theantennas 11, 13 can be formed from any suitable conductive material(s)including metals and conductive non-metallic materials. Examples ofmetals that can be used include, but are not limited to, copper or gold.Another example of a material that can be used is non-metallic materialsthat are doped with metallic material to make the non-metallic materialconductive.

In FIGS. 2A-2C, the antennas 11, 13 within each one of the arrays 33, 33a have different geometries from one another. In addition, FIGS. 3A-Cillustrate plan views of additional examples of the antennas 11, 13having different geometries from one another. The examples in FIGS.2A-2C and 3A-C are not exhaustive and many different configurations arepossible.

FIG. 3A illustrates a plan view of an antenna array having two antennaswith different geometries. In this example, the antennas 11, 13 areillustrated as substantially linear strips each with a lateral lengthL₁₁, L₁₃, a lateral width W₁₁, W₁₃, and a perimeter edge E₁₁, E₁₃. Theperimeter edges E₁₁, E₁₃ extend around the entire periphery of theantennas 11, 13 and bound an area in plan view. In this example, thelateral length L₁₁, L₁₃ and/or the lateral width W₁₁, W₁₃ is greaterthan a thickness dimension of the antennas 11, 13 extending into/fromthe page when viewing FIG. 3A. In this example, the antennas 11, 13differ in geometry from one another in that the shapes of the ends ofthe antennas 11, 13 differ from one another. For example, when viewingFIG. 3A, the right end 42 of the antenna 11 has a different shape thanthe right end 44 of the antenna 13. Similarly, the left end 46 of theantenna 11 may have a similar shape as the right end 42, but differsfrom the left end 48 of the antenna 13 which may have a similar shape asthe right end 44. It is also possible that the lateral lengths L₁₁, L₁₃and/or the lateral widths W₁₁, W₁₃ of the antennas 11, 13 could differfrom one another.

FIG. 3B illustrates another plan view of an antenna array having twoantennas with different geometries that is somewhat similar to FIG. 3A.In this example, the antennas 11, 13 are illustrated as substantiallylinear strips each with the lateral length L₁₁, L₁₃, the lateral widthW₁₁, W₁₃, and the perimeter edge E₁₁, E₁₃. The perimeter edges E₁₁, E₁₃extend around the entire periphery of the antennas 11, 13 and bound anarea in plan view. In this example, the lateral length L₁₁, L₁₃ and/orthe lateral width W₁₁, W₁₃ is greater than a thickness dimension of theantennas 11, 13 extending into/from the page when viewing FIG. 3B. Inthis example, the antennas 11, 13 differ in geometry from one another inthat the shapes of the ends of the antennas 11, 13 differ from oneanother. For example, when viewing FIG. 3B, the right end 42 of theantenna 11 has a different shape than the right end 44 of the antenna13. Similarly, the left end 46 of the antenna 11 may have a similarshape as the right end 42, but differs from the left end 48 of theantenna 13 which may have a similar shape as the right end 44. Inaddition, the lateral widths W₁₁, W₁₃ of the antennas 11, 13 differ fromone another. It is also possible that the lateral lengths L₁₁, L₁₃ ofthe antennas 11, 13 could differ from one another.

FIG. 3C illustrates another plan view of an antenna array having twoantennas with different geometries that is somewhat similar to FIGS. 3Aand 3B. In this example, the antennas 11, 13 are illustrated assubstantially linear strips each with the lateral length L₁₁, L₁₃, thelateral width W₁₁, W₁₃, and the perimeter edge E₁₁, E₁₃. The perimeteredges E₁₁, E₁₃ extend around the entire periphery of the antennas 11, 13and bound an area in plan view. In this example, the lateral length L₁₁,L₁₃ and/or the lateral width W₁₁, W₁₃ is greater than a thicknessdimension of the antennas 11, 13 extending into/from the page whenviewing FIG. 3C. In this example, the antennas 11, 13 differ in geometryfrom one another in that the shapes of the ends of the antennas 11, 13differ from one another. For example, when viewing FIG. 3C, the rightend 42 of the antenna 11 has a different shape than the right end 44 ofthe antenna 13. Similarly, the left end 46 of the antenna 11 may have asimilar shape as the right end 42, but differs from the left end 48 ofthe antenna 13 which may have a similar shape as the right end 44. Inaddition, the lateral widths W₁₁, W₁₃ of the antennas 11, 13 differ fromone another. It is also possible that the lateral lengths L₁₁, L₁₃ ofthe antennas 11, 13 could differ from one another.

FIGS. 4A-D are plan views of additional examples of different shapesthat the ends of the transmit and receive antennas 11, 13 can have toachieve differences in geometry. Either one of, or both of, the ends ofthe antennas 11, 13 can have the shapes in FIGS. 4A-D, including in theembodiments in FIGS. 3A-C. FIG. 4A depicts the end as being generallyrectangular. FIG. 4B depicts the end as having one rounded corner whilethe other corner remains a right angle. FIG. 4C depicts the entire endas being rounded or outwardly convex. FIG. 4D depicts the end as beinginwardly concave. Many other shapes are possible.

FIG. 5 illustrates another plan view of an antenna array having sixantennas illustrated as substantially linear strips. In this example,the antennas differ in geometry from one another in that the shapes ofthe ends of the antennas, the lateral lengths and/or the lateral widthsof the antennas differ from one another.

Another technique to achieve decoupling of the antennas is to use anappropriate spacing between each antenna with the spacing beingsufficient to force most or all of the signal(s) transmitted by thetransmit antenna into the target, thereby minimizing the direct receiptof electromagnetic energy by the receive antenna directly from thetransmit antenna. The appropriate spacing can be used by itself toachieve decoupling of the antennas. In another embodiment, theappropriate spacing can be used together with differences in geometry ofthe antennas to achieve decoupling.

Referring to FIG. 2A, there is a spacing D between the transmit antenna11 and the receive antenna 13 at the location indicated. The spacing Dbetween the antennas 11, 13 may be constant over the entire length (forexample in the X-axis direction) of each antenna 11, 13, or the spacingD between the antennas 11, 13 could vary. Any spacing D can be used aslong as the spacing D is sufficient to result in most or all of thesignal(s) transmitted by the transmit antenna 11 reaching the target andminimizing the direct receipt of electromagnetic energy by the receiveantenna 13 directly from the transmit antenna 11, thereby decoupling theantennas 11, 13 from one another.

In addition, there is preferably a maximum spacing and a minimum spacingbetween the transmit antenna 11 and the receive antenna 13. The maximumspacing may be dictated by the maximum size of the housing 29. In oneembodiment, the maximum spacing can be about 50 mm. In one embodiment,the minimum spacing can be from about 1.0 mm to about 5.0 mm.

FIG. 6 schematically depicts another example of a non-invasive analytesensor 50 that forms a portion of another embodiment of a non-invasiveanalyte sensor system. The non-invasive analyte sensor 50 useselectromagnetic energy in the form of light waves at selectedelectromagnetic frequencies to perform non-invasive analyte sensingdescribed herein. The sensor 50 includes a housing 52 and a sensor arraythat includes a plurality of transmit elements 54 each of which can emitelectromagnetic energy in the form of light. In this example, thetransmit elements 54 are disposed in an array surrounding a receiveelement 56 which can be a photodetector. The illustrated example depictsthe array as having a total of twelve of the elements 54 arranged in acircular array around the receive element 56. However, a larger orsmaller number of the elements 54 can be provided in the array. Inaddition, the array can have an arrangement other than being a circulararray. The separate receive element 56 is not necessary if one of theelements 54 is controlled to function as a receive element as describedin detail below with respect to LEDs that can function to both emitlight and detect light.

FIG. 7 illustrates another embodiment similar to FIG. 6. In FIG. 7, eachof the elements 54 are controlled in a manner whereby any one or more ofthe elements 54 can emit light (and thereby function as a transmitelement) and any one or more of the elements 54 can act as a lightdetector (and thereby function as a receive element). In FIG. 7, sincean element 54 can function as a transmit element or as a receiveelement, the use of a separate receive element 56 as in FIG. 6 is notrequired. However, the separate receive element 56 can be included ifdesired. The illustrated example depicts the array as having a total oftwelve of the elements 54 arranged into a 3×4 or 4×3 array. However, alarger or smaller number of the elements 54 can be provided in thearray. In addition, the array can have other arrangements including theelements 54 being disposed in a circular array.

In one embodiment, the elements 54 in FIGS. 6 and 7 may be lightemitting diodes (LEDs) and the array that includes the LEDs can bereferred to as an LED array. LEDs that can be selectively controlled toemit light (i.e. a photoemitter) or detect light (i.e. a photodetector)are known. See Stojanovic et al., An optical sensing approach based onlight emitting diodes, Journal of Physics: Conference Series 76 (2007);Rossiter et al., A novel tactile sensor using a matrix of LEDs operatingin both photoemitter and photodetector modes, Proc of 4th IEEEInternational Conference on Sensors (IEEE Sensors 2005). See also U.S.Pat. No. 4,202,000 the entire contents of which are incorporated hereinby reference.

Referring to FIG. 8, in the embodiments of FIGS. 6 and 7 some or all theelements 54 may be flush with a surface 58 of the housing 52 so thatlight emitted by each transmit element 54 may be transmitted from thesensor 50 and receive element 56 (or one of the elements 54 acting as areceive element) detects returning light. In another embodiment, some orall of the transmit elements 54 may be recessed within the housing 52but the light from each transit element 54 is suitably channeled to theoutside and returning light suitably channeled to the receive elements54. In still another embodiment, some or all of the transmit elements 54may project (partially or completely) from the surface 58 of the housing52.

In FIGS. 6 and 7, when the elements 54 are LEDs, the LEDs can becontrolled in a manner whereby any one or more of the LEDs can emitlight. In addition, the receive element 56 of FIG. 6 can act as a lightdetector, or any one or more of the LEDs in FIGS. 6 and 7 can becontrolled to act as a light detector. The LEDs that are used preferablypermit at least two different wavelengths of light to be emitted. Inanother embodiment, at least three or more different wavelengths oflight can be emitted. In one embodiment, each one of the LEDs can emit adifferent wavelength of light. In one embodiment, two or more of theLEDs can emit the same wavelength of light. The LED's can emitwavelengths that are in the human visible spectrum (for example, about380 to about 760 nm) including, but not limited to, wavelengths that arevisibly perceived as blue light, red light, green light, white light,orange light, yellow light, and other colors, as well as emitwavelengths that are not in the human visible spectrum including, butnot limited to, infrared wavelengths. Combinations of wavelengths in thevisible and non-visible spectrums may also be used. The light wavesemitted by the sensor 50 function in a manner similar to the RF wavesemitted by the sensor 5 in FIGS. 1-5 since both are electromagneticwaves. For example, referring to FIG. 8, light waves 60 emitted by theelement 54 penetrate into a target and reflect from an analyte in thetarget to form the returning light waves 62 which are detected, forexample the receive element 56 (or by an LED acting as a receiveelement).

With reference now to FIG. 9, one embodiment of a method 70 fordetecting at least one analyte in a target is depicted. The method inFIG. 9 can be practiced using any of the embodiments of sensor devicesdescribed herein including the sensor 5 and the sensor 50. In order todetect the analyte, the sensor 5, 50 is placed in relatively closeproximity to the target. Relatively close proximity means that thesensor 5, 50 can be close to but not in direct physical contact with thetarget, or alternatively the sensor 5, 50 can be placed in direct,intimate physical contact with the target. The spacing between thesensor 5, 50 and the target can be dependent upon a number of factors,such as the power of the transmitted signal. Assuming the sensor 5, 50is properly positioned relative to the target, at box 72 the transmitsignal is generated, for example by the transmit circuit 15. Thetransmit signal is then provided to the transmit element (11 or 54)which, at box 74, transmits the transmit signal toward and into thetarget. At box 76, a response resulting from the transmit signalcontacting the analyte(s) is then detected by the receive element (13,54, or 56). The receive circuit obtains the detected response from thereceive element and provides the detected response to the controller. Atbox 78, the detected response can then be analyzed to detect at leastone analyte. The analysis can be performed by the controller 19 and/orby the external device 25 and/or by the remote server 27.

Referring to FIG. 10, the analysis at box 78 in the method 70 can take anumber of forms. In one embodiment, at box 80, the analysis can simplydetect the presence of the analyte, i.e. is the analyte present in thetarget. Alternatively, at box 82, the analysis can determine the amountof the analyte that is present.

For example, in the case of the sensor being the sensor 5 and the signalbeing in the radio frequency range, the interaction between thetransmitted signal and the analyte may, in some cases, increase theintensity of the signal(s) that is detected by the receive antenna, andmay, in other cases, decrease the intensity of the signal(s) that isdetected by the receive antenna. For example, in one non-limitingembodiment, when analyzing the detected response, compounds in thetarget, including the analyte of interest that is being detected, canabsorb some of the transmit signal, with the absorption varying based onthe frequency of the transmit signal. The response signal detected bythe receive antenna may include drops in intensity at frequencies wherecompounds in the target, such as the analyte, absorb the transmitsignal. The frequencies of absorption are particular to differentanalytes. The response signal(s) detected by the receive antenna can beanalyzed at frequencies that are associated with the analyte of interestto detect the analyte based on drops in the signal intensitycorresponding to absorption by the analyte based on whether such dropsin signal intensity are observed at frequencies that correspond to theabsorption by the analyte of interest. A similar technique can beemployed with respect to increases in the intensity of the signal(s)caused by the analyte.

Detection of the presence of the analyte can be achieved, for example,by identifying a change in the signal intensity detected by the receiveantenna at a known frequency associated with the analyte. The change maybe a decrease in the signal intensity or an increase in the signalintensity depending upon how the transmit signal interacts with theanalyte. The known frequency associated with the analyte can beestablished, for example, through testing of solutions known to containthe analyte. Determination of the amount of the analyte can be achieved,for example, by identifying a magnitude of the change in the signal atthe known frequency, for example using a function where the inputvariable is the magnitude of the change in signal and the outputvariable is an amount of the analyte. The determination of the amount ofthe analyte can further be used to determine a concentration, forexample based on a known mass or volume of the target. In an embodiment,presence of the analyte and determination of the amount of analyte mayboth be determined, for example by first identifying the change in thedetected signal to detect the presence of the analyte, and thenprocessing the detected signal(s) to identify the magnitude of thechange to determine the amount.

In operation of either one of the sensors 5, 50 of FIGS. 1-8, one ormore frequency sweeps or scan routines can implemented. The frequencysweeps can be implemented at a number of discrete frequencies (rfrequency targets) over a range of frequencies. An example of afrequency sweep in a non-invasive analyte sensor using frequencies inthe radio/microwave frequency range is described in WO 2019/217461, theentire contents of which are incorporated herein by reference. In thecase of the sensor 50, a frequency sweep can be implemented with thesensor 50 at a number of discrete electromagnetic frequencies in thevisible wavelength range over a range of electromagnetic frequenciesbased on the different wavelengths of the LEDs. A response spectra isdetected by the receive element 56 or by the element 54 functioning as aphotodetector with the response spectra being correlated to a particularanalyte and analyte concentration.

An example of a frequency sweep is illustrated in FIG. 11 wherefrequency is plotted against time. The sweep occurs over a frequencyrange from a start frequency to an end frequency. In one embodiment, inthe case of the radio frequency sensor 5, the start frequency can beabout 10 kHz and the end frequency can be about 100 GHz. However, thestart frequency of the frequency sweep can be about 100 GHz and the endfrequency can be about 10 kHz. In the case of the sensor 50, the startfrequency can be about 400 THz (i.e. about 380 nm) and the end frequencycan be about 790 THz (i.e. about 760 nm). However, the start frequencyof the frequency sweep can be about 790 THz and the end frequency can beabout 400 THz.

At selected target frequencies within the frequency range, the transmitelement emits at least one transmit signal at the associated targetfrequency. The sweep includes a plurality of frequency steps 1, 2 . . .n each of which defines an incremental change (increase or decrease) infrequency from one target frequency to the next target frequency. Thefrequency steps in the frequency sweep can be the same as one another orsome of the frequency steps can be different from one another. Forexample, in one embodiment, each frequency step can be 1 Hz or 1 kHz or1 THz, 5 Hz or 5 kHz or 5 THz, 10 Hz or 10 kHz or 10 THz, etc. At theconclusion of emitting a signal at a particular target frequency, thecontroller initiates a step change to the next target frequency byincreasing or decreasing the frequency by the frequency step to transmitone or more signals at the next target frequency.

Each frequency step has an associated operation time. The operation timeis the total time (processor clock time) from the completion ofoperation at one target frequency to the completion of operation at thenext target frequency (i.e. the end of the processor clock at the onetarget frequency to the end of the processor clock at the next targetfrequency), or from the start of operation at one target frequency tothe start of operation at the next target frequency. Each operation timeis made-up of a plurality of sub-operations 100 and associatedsub-operation times which are operational delays within and that make upthe block of operation time. Sub-operations 100 include all theoperational delays that occur in transitioning from one target frequencyto the next target frequency and generating and transmitting the signalat the next target frequency. For example, examples of sub-operationtime delays can include, but are not limited to: the time to write datato a memory chip; the time to read data/instructions from memory or theprocessor; the time to step from a completed target frequency to thenext target frequency; the time to generate a signal to be transmittedat the next target frequency; the time to transmit the signal from thesignal generator to the transmit element; the time to transmit one ormore of the signals by the transmit element at the next targetfrequency; etc. The number and times of the sub-operation time delays ineach block of operation time can vary.

In one embodiment, the frequency sweep can be controlled by thecontroller so that all of the blocks of operation times across theentire sweep are the same as one another. For example, in oneembodiment, each block of operation time over the entire frequency sweepcan be 30 μs. In another embodiment, the frequency sweep can becontrolled so that at least some of the blocks of operation times acrossthe entire frequency sweep differ from one another. For example, in oneembodiment, one or more of the operation times can be 30 μs, one or moreof the operation times can be 25 μs, one or more of the operation timescan be 35 μs, one or more of the operation times can be 100 ms, etc.When controlling the frequency sweeps, the controller can introducedelay into one or more operation times to achieve the desired operationtime. For example, in one of the sub-operations 100 at a particulartarget frequency, the signal at that particular target frequency may betransmitted multiple times instead of transmitted a single time. Inanother embodiment, the controller can accelerate or eliminate one ormore sub-operations 100, thereby accelerating one or more of theoperation times. For example, in one of the sub-operations 100 at aparticular target frequency, the signal at that particular targetfrequency may be transmitted a single time instead of transmittedmultiple times. Any technique(s) for achieving the desired operationtimes can be implemented.

However, in one embodiment, when multiple frequency sweeps areimplemented, it is preferred that the blocks of operation times of thefrequency steps at each target frequency in each frequency sweep matcheach other. For example, assuming first and second frequency sweeps, thefrequency sweeps can be controlled to achieve the following:

TABLE 1 Frequency Sweep 1 Frequency Sweep 2 Target Operation time TargetOperation time Step Frequency (μs) Step Frequency (μs) 1 F1 30 1 F1 30 2F2 30 2 F2 30 3 F3 40 3 F3 40 · · · · · · · · · · · · N Fn 50 n Fn 50

As indicated in Table 1, some of the operation times within the twofrequency sweeps are shown as being different from one another. However,it may be preferred that the frequency sweeps are controlled such thatthe same steps in each frequency sweep have the same operation times.For example, step 1 in each of frequency sweep 1 and frequency sweep 2at the target frequency F1 have the same operation time; step 2 in eachof frequency sweep 1 and frequency sweep 2 at the target frequency F2have the same operation time; etc. This described control helps toensure that the two frequency sweeps are performed as close toidentically as possible so that the resulting return signals from eachfrequency sweep can be obtained under as close to identical conditionsas possible, which helps when comparing and analyzing the resultingreturn signals from the frequency sweeps so that an apples-to-applescomparison between the two frequency sweeps can be performed. AlthoughTable 1 shows two frequency sweeps, a larger number of frequency sweepscan be performed, and each frequency sweep can be controlled in themanner described with respect to frequency sweeps 1 and 2.

Each frequency sweep need not encompass the same frequency range. Forexample, one frequency sweep can have a start frequency Fs1 and an endfrequency Fe2, while a second frequency sweep can have a start frequencyFs3 and an end frequency Fe4. Fs1 can be equal to, less than or greaterthan Fs3, and Fe2 can be less than, equal to, or greater than Fe4.However, the frequency sweeps should have at least some overlappingfrequency range with one another, where in the overlapping range thefrequency sweeps are controlled as described above and in Table 1 sothat the frequency steps in the overlapping range in each frequencysweep are the same and the operation times of the frequency steps in theoverlapping range are identical to one another (i.e. as indicated inTable 1 above, in the overlapping range, the operation times of thefirst frequency steps of the first frequency sweep are identical to thecorresponding operation times of the second frequency steps of thesecond frequency sweep). However, as explained above, in one embodiment,in the overlapping range, the operation times of at least some of thefirst frequency steps of the first frequency range may not be equal toone another, and the operation times of at least some of the secondfrequency steps of the second frequency range may not be equal to oneanother. In another embodiment, in the overlapping range or across theentire range of each frequency sweep, the operation times of thefrequency steps in one of the frequency sweeps may be equal to oneanother, and the operation times of the frequency steps in the otherfrequency sweep may be equal to one another.

The frequency sweeps described herein may occur in succession one afterthe other in a relatively short overall timeframe. In anotherembodiment, the frequency sweeps described herein do not occur insuccession but are instead spaced from one another over a relativelylong time period. For example, one frequency sweep can occur on one dayand another frequency sweep can occur on a different day.

In another embodiment, instead of implementing multiple frequencysweeps, a single frequency sweep can be implemented. In the singlefrequency sweep, the blocks of operation time may be the same as oneanother or some of the blocks of operation time may differ from oneanother.

In another embodiment, a non-invasive sensor can include aspects of bothof the sensors 5, 50. For example, a sensor can include both two or moreantennas as described herein as well as two or more of the LEDsdescribed herein. The antennas and the LEDs can be used together todetect an analyte. In another embodiment, the antennas can be used toperform a primary detection while the LEDs can confirm the primarydetection by the antennas. In another embodiment, the LEDs can be usedto perform a primary detection while the antennas can be used to confirmthe primary detection by the LEDs. In another embodiment, the antennas(or the LEDs) can be used to calibrate the sensor while the LEDs (or theantennas) can perform the sensing.

The terminology used in this specification is intended to describeparticular embodiments and is not intended to be limiting. The terms“a,” “an,” and “the” include the plural forms as well, unless clearlyindicated otherwise. The terms “comprises” and/or “comprising,” whenused in this specification, specify the presence of the stated features,integers, steps, operations, elements, and/or components, but do notpreclude the presence or addition of one or more other features,integers, steps, operations, elements, and/or components.

The examples disclosed in this application are to be considered in allrespects as illustrative and not limitative. The scope of the inventionis indicated by the appended claims rather than by the foregoingdescription; and all changes which come within the meaning and range ofequivalency of the claims are intended to be embraced therein.

The invention claimed is:
 1. A sensor system, comprising: a detectorarray having at least one transmit element and at least one receiveelement, the at least one transmit element is positioned and arranged totransmit a transmit signal into a target, and the at least one receiveelement is positioned and arranged to detect a response resulting fromtransmission of the transmit signal by the at least one transmit elementinto the target; a transmit circuit that is electrically connectable tothe at least one transmit element, the transmit circuit is configured togenerate the transmit signal to be transmitted by the at least onetransmit element, the transmit signal is in a radio frequency or visiblerange of the electromagnetic spectrum; a receive circuit that iselectrically connectable to the at least one receive element, thereceive circuit is configured to receive the response detected by the atleast one receive element; and a control system connected to thetransmit circuit and configured to implement at least first and secondfrequency sweeps by the at least one transmit element, the firstfrequency sweep occurs over a first frequency range from a startfrequency to an end frequency, the second frequency sweep occurs over asecond frequency range from a start frequency to an end frequency, andthe first frequency range and the second frequency range overlap oneanother; the first frequency range and the second frequency range wherethey overlap have first frequency steps and second frequency steps,respectively; the first frequency steps are the same as the secondfrequency steps; each frequency step of the first frequency steps andthe second frequency steps has an associated operation time, and theoperation times of the first frequency steps are identical to theoperation times of the second frequency steps; the at least one transmitelement and the at least one receive element comprise antennas, and thefirst frequency range and the second frequency range are each in a radioor microwave frequency range of the electromagnetic spectrum.
 2. Thesensor system of claim 1, wherein the operation times of at least someof the first frequency steps are not equal to one another, and theoperation times of at least some of the second frequency steps are notequal to one another.
 3. The sensor system of claim 1, wherein theoperation times of the first frequency steps are equal to one another,and the operation times of the second frequency steps are equal to oneanother.
 4. The sensor system of claim 1, wherein each operation timeincludes a plurality of sub-operations.
 5. The sensor system of claim 4,wherein the plurality of sub-operations of at least one of the operationtimes include a plurality of transmissions of a frequency by the atleast one transmit element.
 6. The sensor system of claim 1, wherein thedetector array, the transmit circuit, the receive circuit, and thecontrol system are incorporated into a wearable watch or a tabletopdevice.
 7. The sensor system of claim 1, wherein the target is a bodyfluid, and the sensor system is configured to sense blood glucose, bloodalcohol, white blood cells, or luteinizing hormone.
 8. A method ofoperating a sensor system that includes a detector array having at leastone transmit element and at least one receive element, the at least onetransmit element is positioned and arranged to transmit a transmitsignal into a target, and the at least one receive element is positionedand arranged to detect a response resulting from transmission of thetransmit signal by the at least one transmit element into the target, atransmit circuit that is electrically connectable to the at least onetransmit element where the transmit circuit is configured to generatethe transmit signal to be transmitted by the at least one transmitelement, the transmit signal is in a radio frequency or visible range ofthe electromagnetic spectrum, and a receive circuit that is electricallyconnectable to the at least one receive element where the receivecircuit is configured to receive a response detected by the at least onereceive element, the method comprising: controlling the sensor system toimplement at least a first frequency sweep and a second frequency sweepby the at least one transmit element, the first frequency sweep occursover a first frequency range from a start frequency to an end frequency,the second frequency sweep occurs over a second frequency range from astart frequency to an end frequency, and the first frequency range andthe second frequency range overlap one another, the first frequencyrange and the second frequency range where they overlap have firstfrequency steps and second frequency steps, respectively; the firstfrequency steps are the same as the second frequency steps; eachfrequency step of the first frequency steps and the second frequencysteps has an associated operation time, and the operation times of thefirst frequency steps are identical to the operation times of the secondfrequency steps, wherein the at least one transmit element and the atleast one receive element comprise antennas, and the first frequencyrange and the second frequency range are each in a radio or microwavefrequency range of the electromagnetic spectrum.
 9. The method of claim8, comprising controlling the sensor system so that the operation timesof at least some of the first frequency steps are not equal to oneanother, and the operation times of at least some of the secondfrequency steps are not equal to one another.
 10. The method of claim 8,comprising controlling the sensor system so that the operation times ofthe first frequency steps are equal to one another, and the operationtimes of the second frequency steps are equal to one another.
 11. Themethod of claim 8, comprising controlling the sensor system so that eachoperation time includes a plurality of sub-operations.
 12. The method ofclaim 11, comprising controlling the sensor system so that the pluralityof sub-operations of at least one of the operation times include aplurality of transmissions of a frequency by the at least one transmitelement.
 13. The method of claim 8, wherein the detector array, thetransmit circuit, the receive circuit, and the control system areincorporated into a wearable watch or a tabletop device.
 14. The methodof claim 8, wherein the target is a body fluid, and the sensor system isconfigured to sense blood glucose, blood alcohol, white blood cells, orluteinizing hormone.